Gliding is one small, and relatively irrelevant part of the job... regardless how this sounds now. Few years ago, some Swiss Uni made research and in Wengen, which is super long and considered as one of races, where glide is more important, and they found out, skis are flat on for whole 7 sec. In 2min 30sec long race, they had pure glide for about 4% of time. Sure it's enough to to determine winner, of both skiers had same skiing for other 2min 23sec, but even on "glide" DH races, there's more important factors then glide.
Otherwise, I would say boots are thing that make biggest difference. Setup for perfect glide is anything but setup for perfect skiing for rest of course. So finding right compromise between these two, completely opposite thing, which allows you to be fast in corners and still enable you to glide relatively well is crucial, but not really easy thing to do.